Exim: Two buffer overflows

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200501-23 / exim
Release Date	January 12, 2005
Latest Revision	January 12, 2005: 01
Impact	high
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
mail-mta/exim	< 4.43-r2	>= 4.43-r2	All supported architectures

Related bugreports: #76893

Synopsis

Buffer overflow vulnerabilities, which could lead to arbitrary code execution, have been found in the handling of IPv6 addresses as well as in the SPA authentication mechanism in Exim.

2. Impact Information

Background

Exim is an highly configurable message transfer agent (MTA) developed at the University of Cambridge.

Description

Buffer overflows have been found in the host_aton() function (CAN-2005-0021) as well as in the spa_base64_to_bits() function (CAN-2005-0022), which is part of the SPA authentication code.

Impact

A local attacker could trigger the buffer overflow in host_aton() by supplying an illegal IPv6 address with more than 8 components, using a command line option. The second vulnerability could be remotely exploited during SPA authentication, if it is enabled on the server. Both buffer overflows can potentially lead to the execution of arbitrary code.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All Exim users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=mail-mta/exim-4.43-r2"

4. References

Updated January 12, 2005

Summary: This is a Gentoo Linux Security Advisory

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